There Is A Gigantic Gas Cloud On A Collision Course With The Milky Way

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NASA
has released a new video on the notorious Smith Cloud, a high-velocity cloud
that is expected to crash into the Milky Way in about 30 million years.

The
cloud has a mass of 2 million Suns and is moving at 310 kilometers (193
miles) per second. It was first discovered by astronomer Gail Smith in 1963,
and for many years it was considered just one of the several high-velocity
clouds around the Milky Way.

This
idea changed in the mid-2000s when astronomers looked at the Smith Cloud with
the Green Bank radio telescope in West Virginia, and discovered that it was on
a collision course with our own galaxy.

Suddenly,
we know where it is going but not where it came from, so in the last few years,
astronomers looked into its potential origin. Their findings were
published early this year.

"There
are two leading theories," Andrew Fox, an astronomer at the Space
Telescope Science Institute who led the research, said in the video.
"One is that it was blown out of the Milky Way, perhaps by a cluster of
supernova explosions. The other is that the Smith Cloud is an extragalactic
object that has been captured by the Milky Way."

The
team used the Hubble Space Telescope to carefully analyze the light absorbed by
the cloud. Thanks to this technique, they were able to estimate the abundance
of different elements in the Smith Cloud. The scientists discovered that the
abundance of sulfur in the cloud is similar to the abundance of sulfur in the
outer disk of the Milky Way, suggesting that the first hypothesis is the
correct one.

"The
cloud appears to have been ejected from within the Milky Way and is now falling
back," Fox added. "The cloud is fragmenting and evaporating as it
plows through a halo of diffuse gas surrounding our galaxy. It's basically
falling apart.”

Although
it’s losing pieces, the cloud will still be quite big when it hits our galaxy
in the future. The Smith Cloud will not cause any damage, but astronomers
expect that its large gas reservoir will be compressed and turned into many new
stars as it re-enters our galaxy.